How one power plant is turning away from coal to embrace wood pellets and straw

Something of a biomass revolution is taking place in Denmark. Earlier this year Danish energy company, DONG Energy, announced it would stop "all use of coal" by 2023 and look to focus on sustainable biomass instead.

At the Avedøre Power Station, on the outskirts of Copenhagen, a transformation has taken place: between 2015 and 2016 Avedøre 1, one of its power station units, was converted to use wood pellets rather than coal.

The Avedøre 2 unit uses natural gas, oil, straw and wood pellets. DONG Energy says the biomass system has a capacity of 45 megawatts and is able to take 25 tonnes of straw every hour.

Today, according to DONG Energy, the Avedøre facility is "able to run 100 percent on sustainable biomass."

The impact on the environment is being keenly felt.

"When we look at the life cycle assessment of the green energy that we are using, the wood pellets and the straw, we are reducing the CO2 emissions by approximately 90 percent compared to when we were using coal," Ole Thomsen, senior vice president at Avedøre Power Station, told CNBC's Sustainable Energy.

Thomsen went on to explain that most of the biomass being used was sourced from Baltic countries that are home to a big timber industry.

While the environmental benefits may be clear, cost was still something to be considered, although legislation is helping to smooth the transition.

"Coal is still a cheaper fuel than wood pellets," Thomsen said. "But when you're using coal for heat production there is a CO2 tax on it, when you're using wood pellets for heat production there is no CO2 tax."

"All in all, this means that we are able to produce green energy for the same price for the customer as when we were using coal."